Right. I did know some alkalinity was necessary after my last stout I did. The water had 40 ppm of total alkalinity. I came in at 5.1, added a half teaspoon of chalk and nothing. This is why this time I'm using baking soda instead of chalk and why I'm adjusting my water to 62 ppm total alkalinity. Do you think I'd need to be any higher? It says I'll be adding 30 ppm of sodium which from what I've heard so far is totally acceptable.

As for the epsom salts, I thought magnesium was important for yeast health? Do you mean epsom salts would better suit a bitter aggressive beer because of the sulfates that come along with it? If so I've taken those into account by balancing my sulfates with chlorides.

The Mg supplies its own bitterness or tartness perception, beyond what the sulfate provides. If the beer has a bitter focus, then adding the Mg can be a good idea. As mentioned by others, malt provides enough Mg to the wort for yeast health, so additional should not be necessary unless desired for taste.

The pH response with the use of chalk is typical of many user reports I've been given. It just doesn't work effectively. To anyone brewing with RO water or low alkalinity tap water, get a pound of pickling lime and learn to use that. A pound should last a typical homebrewer a really long time since you don't use much. If you have homebrewing buddies, split the pound with them. Be sure to keep the lime in a tightly sealed container since it will eventually revert to chalk if moist air gets to it.

If that 5.1 reading was at room temperature, it was a little too low and confirms the need for alkalinity.

The 30 ppm Na should be OK. I like a touch in my beers. But it would be OK to not have it in there at all.

The Mg supplies its own bitterness or tartness perception, beyond what the sulfate provides. If the beer has a bitter focus, then adding the Mg can be a good idea. As mentioned by others, malt provides enough Mg to the wort for yeast health, so additional should not be necessary unless desired for taste.

The pH response with the use of chalk is typical of many user reports I've been given. It just doesn't work effectively. To anyone brewing with RO water or low alkalinity tap water, get a pound of pickling lime and learn to use that. A pound should last a typical homebrewer a really long time since you don't use much. If you have homebrewing buddies, split the pound with them. Be sure to keep the lime in a tightly sealed container since it will eventually revert to chalk if moist air gets to it.

If that 5.1 reading was at room temperature, it was a little too low and confirms the need for alkalinity.

The 30 ppm Na should be OK. I like a touch in my beers. But it would be OK to not have it in there at all.

Didn't know that about adding Magnesium. I'll forget about that then and adjust accordingly. I will also look into pickling lime. I hit 5.1 at mash temp, not room temp.

Whoops! Didn't know that. Well I've only done a couple of batches doing that. Kind of wish I would have gotten colorphast strips now. They seem simpler and I wouldn't have to worry about them crapping out eventually.

Was the other poster accurate in saying 5.1 mash temp is 5.4 room temp? So it's always .3 higher at room temp?

Didn't know that about adding Magnesium. I'll forget about that then and adjust accordingly. I will also look into pickling lime. I hit 5.1 at mash temp, not room temp.

5.1 now at mash temperature for a stout in 100% RO water makes a lot of sense and indicates a well calibrated meter.

If you don't want to react to your mash pH you can run a quick test while heating the mash water. Determine the % of your grains (individual grain/total grain in the beer) and measure that out so you have a total grain bill that adds up to 100 grams. Determine your mash thickness (about 300 mL (grams) of your brewing water) and heat that up in the microwave to 160F in a mason jar. Crush the 100 grams of grain in a electric blade-style coffee grinder to a fine dust and mash for 15 min. Cool a sample, check the pH and make adjustments to acid/base before your actual mash. You'll get pH information before your mash tun is heated.

(I skip the water bath now shown in the pic and often take the oppertunity to test mash something else and use a calibrated meter for research & planning)

5.1 now at mash temperature for a stout in 100% RO water makes a lot of sense and indicates a well calibrated meter.

If you don't want to react to your mash pH you can run a quick test while heating the mash water. Determine the % of your grains (individual grain/total grain in the beer) and measure that out so you have a total grain bill that adds up to 100 grams. Determine your mash thickness (about 300 mL (grams) of your brewing water) and heat that up in the microwave to 160F in a mason jar. Crush the 100 grams of grain in a electric blade-style coffee grinder to a fine dust and mash for 15 min. Cool a sample, check the pH and make adjustments to acid/base before your actual mash. You'll get pH information before your mash tun is heated.

(I skip the water bath now shown in the pic and often take the oppertunity to test mash something else and use a calibrated meter for research & planning)

No the stout was brewed at a friend's house with his tap water. The tap water has about 40ppm of total alkalinity as said by the water report. I'm starting to brew in a new location and will have to start brewing with RO water since the water is softened.